What comes first - payment or retouching?

I'm fairly new to retouching business and I have always retouched on TF basis only so far. Hence I would have three questions:

1) I'm wondering what comes first: payment by the client before you do any retouching or you retouch the pictures first and after delivering them to the client comes their payment. If the letter, what can I do to make sure that I really receive the payment in the end? What's the common practice?

2) How much do you charge for your service (regardless the location as I'd like to do this solely via internet)

3) How do you get payed for your service?

Thank you very much for helping. I can imagine it can't be easy to share these precious information.

Im in the uk and I dont think anyone would pay upfront here especially if you are not known to the client.
I usually do the job and deliver an invoice for payment when they receive their files.
They pay through the bank mostly but the last client arrived with his payment in cash when he collected his originals.

Before the job starts, send them an estimate of how much you think it is going to cost, with a little line in there "any work asked for outside of this estimate will be charged at an additional 150 euro's an hour" and ask your client to sign/agree with that estimate.

Then do the job.

Then send them the bill for the ammount they are supposed to pay you.

The ammount depends on a lot of things, the client, your skills, the project, where you are, etc.

It looks like nobody likes to pay before hand. But I've seen this method. The artist does the job, and sends the client, one of two forms: A smaller version of his/her work, or the original size with a watermark, if the client likes it then the retoucher ask for the deposit before sending the work or psd or whatever the contract says. And as gse123 said, an up front deposit it is always a good thing to ask for.

Always, 50% of the estimated cost up front, balance due on delivery of the final product. Thats the way our clients buy most other supplies, why not what we provide? Ever try to check into a hotel and tell the clerk that you will pay them in the morning if you manage to get a good nights sleep or pay for the airplane ride when you get to your destination???

As a rule I always charge up-front before starting working on a batch (a batch can be anything from 1 to 100 images) - or ask the client to make an escrow deposit. Most people don't have a problem with that.

If you are working with the agencies, you will wait 30 - 90 days for payment. This has always been the way. If you are working with small tin pot places, then yes, you will get paid on delivery or beforehand.

But remember, the agencies are where the big bucks are, sure you wait for payment, but you will be getting between $125 - $200 an hour. Not $10 an image! Go figure!

Jeff, sorry if I'm making any confustion by the word "Proof", I mean to say - when I finish the retouch and send it to client with the watermark on it and client approved that he is happy with the work I did, he gets me paid. I think It's clear now.

I give a quote before starting, they agree to this and I begin work. Once completed I send a watermarked copy for customer sign off. If they are happy I invoice them. Once paid, they get the final image. Works for me